Cell structure of IGBT device, IGBT device and IGBT short circuit protection circuit

Abstract

The application provides a cell structure of an IGBT device, an IGBT device and an IGBT short-circuit protection circuit. In the cell structure of the IGBT device, a sampling cell is integrated to form an electrostatic induction transistor in the periphery of an IGBT transistor formed by the main cell of the IGBT device. Thus, the sampling voltage of the weak current on the sampling induction electrode of the sampling cell can be directly obtained, the voltage state of the collector of the IGBT transistor can be fed back in real time, the IGBT device can be safely and quickly detected according to the feedback result whether it is in the off state, and the application has the advantages of simple structure, high integration, fast response, simplified peripheral circuit and low cost.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor devices, and in particular to a cellular structure of an IGBT device, an IGBT device and an IGBT short-circuit protection circuit. Background Art

[0002] Insulated-gate bipolar transistors (IGBTs) combine the voltage control characteristics of MOS transistors (MOS) and the current modulation characteristics of BJT conductivity. They feature high input impedance, low switching losses, high speed, and low voltage drive power. They are widely used in power transmission, high-speed train traction, industrial drives, clean energy, and other fields. Due to their inherent high voltage and high current characteristics, IGBTs are susceptible to short-circuit conditions during application. This means that when simultaneously subjected to high voltage and high current, the device can heat up and burn out within microseconds.

[0003] However, the current IGBT short-circuit protection scheme has disadvantages such as high cost, long delay, and large size, which cannot meet the application requirements of IGBT devices. Summary of the Invention

[0004] The object of the present invention is to provide a cellular structure of an IGBT device, an IGBT device and an IGBT short-circuit protection circuit, which can simplify peripheral circuits and reduce costs.

[0005] To achieve the above-mentioned object, the present invention provides a cell structure of an IGBT device, comprising an IGBT main cell and a sampling cell formed on a drift region of the same first conductivity type, wherein the sampling cell comprises:

[0006] a first conductive type inductive region formed in a top surface layer of the drift region;

[0007] Two doping regions of the second conductivity type are formed in the top of the drift region and are symmetrically distributed on both sides of the sensing region;

[0008] Two blocking trenches are provided in one-to-one correspondence with the two doping regions, and each blocking trench is sandwiched between the corresponding doping region and the sensing region, wherein the depth of the blocking trench is less than the junction depth of the PN junction formed by the sensing region and the doping region;

[0009] a sampling collector region of a second conductivity type, the sampling collector region being arranged at the bottom of the drift region;

[0010] a sampling sensing electrode, disposed on the top surface of the drift region and electrically contacting the sensing region;

[0011] a sampling emitter, disposed on the top surface of the drift region and arranged in one-to-one correspondence with and in electrical contact with the two doping regions;

[0012] The sampling collector is arranged on the bottom surface of the drift region and is in electrical contact with the sampling collector region.

[0013] Optionally, the inner surface of the blocking trench is covered with an insulating dielectric layer and filled with a polysilicon layer; or, the blocking trench is completely filled with an insulating dielectric layer.

[0014] Optionally, the sampling cell further includes a sampling field termination region of the first conductivity type, wherein the sampling field termination region is formed at the bottom of the drift region and stacked on the collector region.

[0015] Optionally, an electron channel is formed between the two blocking grooves, and a potential barrier height of the electron channel depends on a voltage difference between the sampling emitter and the sampling sensing electrode.

[0016] Optionally, the IGBT main cell includes:

[0017] a body region of a second conductivity type formed on top of the drift region;

[0018] a body contact region of a second conductivity type formed in a top surface layer of the body region;

[0019] An emitter region of a first conductivity type is formed in a top surface layer of the body region and is located on both sides of the body contact region;

[0020] a buried region of a first conductivity type formed in the drift region and located below the body region;

[0021] Two gate trenches are formed in the drift region and distributed on both sides of the body region, the depth of each gate trench is greater than the depth of the buried region, and each gate trench has a gate dielectric layer formed therein and is filled with a gate;

[0022] An IGBT collector region of a second conductivity type, wherein the IGBT collector region is arranged at the bottom of the drift region;

[0023] An IGBT emitter is disposed on the top surface of the drift region and is in electrical contact with both the emitter region and the body contact region;

[0024] An IGBT collector is arranged on the bottom surface of the drift region and is in electrical contact with the IGBT collector region.

[0025] Optionally, the IGBT main cell further includes an IGBT field stop region of the first conductivity type, wherein the IGBT field stop region is formed at the bottom of the drift region and stacked on the IGBT collector region.

[0026] Optionally, the IGBT collector region and the sampling collector region are the same ion implantation layer at the bottom of the drift region; the IGBT emitter, the sampling sensing electrode and the sampling emitter are the same metal film, and the IGBT emitter and the sampling emitter are integrated to form the emitter of the cellular structure; the IGBT field stop region and the sampling field stop region are the same ion implantation layer at the bottom of the drift region; the IGBT collector and the sampling collector are the same metal film and are integrated to form the collector of the cellular structure; the gate trench and the blocking trench are formed using the same trench etching process.

[0027] Based on the same inventive concept, the present invention further provides an IGBT device, which includes a plurality of cellular structures of the IGBT devices according to the present invention arranged in parallel.

[0028] Optionally, the IGBT device further includes sampling resistors arranged in a one-to-one correspondence with the cellular structures, and the sampling resistors are connected between the sampling emitter and the sampling sensing electrode of the sampling cells in the corresponding cellular structures.

[0029] Based on the same inventive concept, the present invention also provides an IGBT short-circuit protection circuit, which includes the IGBT device described in the present invention, a protection circuit and a drive circuit, one end of the protection circuit is connected to the sampling sensing electrode of the corresponding sampling cell of the IGBT device, and the other end is connected to one end of the drive circuit, and the other end of the drive circuit is connected to the gate of the corresponding IGBT main cell of the IGBT device.

[0030] Optionally, the IGBT short-circuit protection circuit further includes sampling resistors arranged in a one-to-one correspondence with the cell structures of the IGBT device, and the sampling resistors are connected between the sampling emitter and the sampling sensing electrode of the sampling cell in the corresponding cell structure of the IGBT device.

[0031] Optionally, the protection circuit and the drive circuit are respectively arranged in one-to-one correspondence with the cellular structures of the IGBT device, or multiple cellular structures of the IGBT device share the same protection circuit and the same drive circuit.

[0032] Compared with the prior art, the technical solution of the present invention has at least one of the following beneficial effects:

[0033] 1. A sampling cell is integrated into the cellular structure of the IGBT device to form a static induction transistor (SIT) on the periphery of the IGBT transistor formed by the IGBT main cell. As a result, a weak current with adjustable sampling voltage can be directly obtained on the sampling sensing electrode of the sampling cell, realizing real-time feedback of the voltage state of the collector of the IGBT transistor. Based on this feedback result, it is possible to safely and quickly detect whether the IGBT device is in the shutdown state.

[0034] 2. It has the advantages of fast response, simplified peripheral circuits, and compatibility with the manufacturing process of existing IGBT devices.

[0035] 3. Connecting a sampling resistor in series with the sampling sensing electrode of the sampling cell can generate negative feedback on the current at the sampling sensing electrode. That is, by adjusting the voltage difference between the sampling sensing electrode and the sampling emitter, the barrier height of the electron channel is adjusted, thereby controlling the current at the sampling sensing electrode, suppressing the increase of the current exponential at the sampling sensing electrode, and ensuring that the reliability of the IGBT device itself is not degraded. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a circuit diagram of a conventional IGBT warranty cancellation and detection solution.

[0037] Figure 2 FIG. 1 is a schematic cross-sectional view of a cell structure of an IGBT device according to an embodiment of the present invention.

[0038] Figure 3 FIG. 1 is a schematic cross-sectional view of a cell structure of an IGBT device according to another embodiment of the present invention.

[0039] Figure 4 1 is a sampled cell output characteristic curve in the cell structure of the IGBT device according to an embodiment of the present invention.

[0040] Figure 5 It is a structural diagram of an IGBT short-circuit protection circuit according to an embodiment of the present invention. DETAILED DESCRIPTION

[0041] In the following description, numerous specific details are provided to provide a more thorough understanding of the present invention. However, it will be apparent to those skilled in the art that the present invention can be implemented without one or more of these details. In other examples, certain technical features known in the art are not described to avoid confusion with the present invention. It should be understood that the present invention can be implemented in various forms and should not be construed as limited to the embodiments presented herein. Rather, providing these embodiments will make the disclosure thorough and complete and fully convey the scope of the present invention to those skilled in the art. In the accompanying drawings, the dimensions and relative sizes of layers and regions may be exaggerated for clarity. Identical reference numerals throughout represent identical elements. It should be understood that when an element or layer is referred to as being "on" or "connected to" another element or layer, it may be directly on or connected to the other element or layer, or there may be intervening elements or layers. Conversely, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there may be no intervening elements or layers. Spatially relative terms such as "below," "on the back side of," "back side," "on," "on the front side of," and "front side" may be used herein for convenience of description to describe the relationship of one element or feature shown in a figure to other elements or features. It should be understood that spatially relative terms are intended to encompass different orientations of the device in use and operation, in addition to the orientation shown in the figures. For example, if the device in the figures is flipped, then an element or feature described as "below," "on the back side of," or "on the back side" would be oriented "on" the other element or feature. The device may be oriented differently (rotated 90 degrees or in other orientations), and the spatial descriptors used herein should be interpreted accordingly. The terminology used herein is intended only to describe specific embodiments and is not intended to limit the present invention. When used herein, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "comprising" is used to identify the presence of a feature, step, operation, element, and / or component, but does not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. As used herein, the term "and / or" includes any and all combinations of the associated listed items.

[0042] The technical solutions proposed by the present invention are further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in a very simplified form and are not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0043] The inventors have found that there are currently two mainstream solutions for IGBT short-circuit protection: one is the IGBT desaturation detection solution, which directly samples the voltage VCE between the emitter E and collector C of the IGBT and uses the desaturation characteristics of the IGBT when it is short-circuited to detect whether the IGBT is in a short-circuit state. Figure 1 As shown, since this solution requires sampling high voltages exceeding several hundred volts, it is necessary to install corresponding high-voltage diodes D and protection circuits in the peripheral circuit function to prevent the high voltage from directly entering the drive circuit used to drive the IGBT. In other words, this solution has the disadvantage of high peripheral circuit costs. Another solution is to use a Hall current sensor. Specifically, it uses the fact that the current of the IGBT when it is short-circuited will far exceed the normal operating current of the IGBT to determine whether it is in a short-circuit state. Due to the use of a Hall current sensor, this solution has the disadvantages of high delay and large size.

[0044] Based on this, the present invention provides a new cellular structure of an IGBT device, an IGBT device and an IGBT short-circuit protection circuit, so as to integrate the sampling structure into the cellular structure of the IGBT device, thereby achieving the advantages of simplifying the peripheral circuit, real-time feedback and improving system reliability.

[0045] Please refer to Figure 2 An embodiment of the present invention provides a cell structure of an IGBT device, including a collector layer (C) 103, a collector region 102 of a second conductivity type (e.g., P-type), a field stop layer 101 of a first conductivity type (e.g., N-type), a drift region 100 of a first conductivity type (e.g., N-type), an isolation dielectric layer 111, an emitter layer (E) 112, and an IGBT main cell I and a sampling cell II formed on the same first conductivity type drift region (N-) 100, which are stacked sequentially from bottom to top.

[0046] Specifically, the IGBT main cell 1 includes: two gate trenches 104a, a buried region 107 of a first conductivity type, a body region 108 of a second conductivity type, a body contact region 110 of a second conductivity type, an emitter region 109a of a first conductivity type, an IGBT emitter, an IGBT field stop region of a first conductivity type, an IGBT collector region of a second conductivity type, and an IGBT collector. The body region 108 is formed on the top of the drift region 100, the body contact region 110 is formed in the top surface layer of the body region 108, the emitter region 109a is formed in the top surface layer of the body region 108 and is located on both sides of the body contact region 110, and the buried region 107 is formed in the drift region 100 and is located below the bottom of the body region 108. The top of the buried region 107 can overlap the bottom of the body region 108. Two gate trenches 104 a are formed in the drift region 100 and are distributed on both sides of the body region 108. The depth of each gate trench 104 a is greater than the depth of the buried region 107 (i.e., greater than the junction depth of the PN junction formed by the body region 108 and the buried region 107), to ensure that the channel formed on the sidewall of the gate trench can extend to the drift region 100. The inner surface of each gate trench 104 a is covered with a gate dielectric layer 105 and filled with a gate 106.

[0047] In addition, the body contact region 110 can be independent of the emitter regions 109a on both sides, or they can be close to each other, and the body contact region 110 and the emitter regions 109a on both sides are electrically in contact with the IGBT emitter, that is, the IGBT emitter short-circuits the body contact region 110 and the emitter regions 109a on both sides.

[0048] Sampling cell II includes two blocking trenches 104b, a sensing region 109b of the first conductivity type, two doped regions 113 of the second conductivity type, a sampling collector region of the second conductivity type, a sampling sensing electrode Sense, a sampling emitter, and a sampling collector. The sensing region 109b is formed in the top surface layer of the drift region 100, and the doped regions 113 are formed in the top of the drift region 100 and symmetrically distributed on both sides of the sensing region 109b. The two blocking trenches 104b are arranged in a one-to-one correspondence with the two doped regions 113, and each blocking trench 104b is sandwiched between a corresponding doped region 113 and the sensing region 109b. The depth of each blocking trench 104b is less than the junction depth of the PN junction formed by the sensing region 109b and the doped region 113, but greater than the depth of the sensing region 109b.

[0049] In this embodiment, the blocking trench 104b in the sampling cell II can block the lateral diffusion of the doped region 113. An electron channel can be formed between the blocking trenches 104b. The depth of the PN junction formed by the doped region 113 and the drift region 100 is greater than the depth of the blocking trench 104b, which can form an electron channel barrier that blocks the electron emission from the sampling sensing electrode Sense. Therefore, by adjusting the voltage difference VSE between the sampling sensing electrode Sense and the sampling emitter, the height of the electron channel barrier formed between the blocking trenches 104b can be adjusted.

[0050] In this embodiment, each blocking trench 104b and the gate trench 104a are formed using the same etching process and the same filling process, that is, the inner surface of the blocking trench 104b is covered with a gate dielectric layer 105 and filled with the material of the gate 106. At this time, the material of the gate 106 in the blocking trench 104b serves as the emitter.

[0051] However, the technical solution of the present invention is not limited thereto. In other embodiments of the present invention, the blocking trench 104b may be formed separately from the gate trench 104a. Thus, the depth, line width, and filling material of the blocking trench 104b may be different from those of the gate trench 104a. For example, please refer to Figure 3 The inner surface of the blocking trench 104 b is covered with a gate dielectric layer 105 and further filled with an insulating dielectric layer 105 ′, and the inner surface of the gate trench 104 a is covered with a gate dielectric layer 105 and further filled with a gate 106 .

[0052] In addition, in this embodiment, the portion of the field stop layer 101 located in the region of the IGBT main cell I serves as the IGBT field stop region of the IGBT main cell I, and the portion of the field stop layer 101 located in the region of the sampling cell II serves as the sampling field stop region of the sampling cell II; the portion of the collector layer 103 located in the region of the IGBT main cell I serves as the IGBT collector of the IGBT main cell I, and the portion of the collector layer 103 located in the region of the sampling cell II serves as the sampling collector of the sampling cell II; the portion of the collector region 102 located in the region of the IGBT main cell I serves as the IGBT collector region of the IGBT main cell I, and the portion of the collector region 102 located in the region of the sampling cell II serves as the sampling collector region of the sampling cell II; the portion of the emitter layer 112 located in the region of the IGBT main cell I serves as the IGBT collector region of the IGBT main cell I The IGBT emitter of the sampling cell II is provided. The portion of the emitter layer 112 located in the region of the sampling cell II and electrically contacting the doped region 113 serves as the sampling emitter of the sampling cell II. The portion of the emitter layer 112 located in the region of the sampling cell II and electrically contacting the sensing region 109 b serves as the sampling sensing electrode of the sampling cell II. The portion of the isolation dielectric layer 111 located in the region of the IGBT main cell I serves as an isolation dielectric between the IGBT emitter of the IGBT main cell I and the edge region of the emitter region 109 a and the gate 106. The portion of the isolation dielectric layer 111 located in the region of the sampling cell II serves as an isolation dielectric between the sampling emitter of the sampling cell II and the corresponding portion of the doped region 113, and between the sampling sensing electrode Sense and the corresponding portion of the sensing region 109 b.

[0053] The drift region 100 may be made of any suitable semiconductor material, such as silicon, germanium, silicon carbide, gallium arsenide, gallium nitride, etc. The gate dielectric layer 105 may be made of silicon oxide, etc., and the gate 106 may be made of doped polysilicon, etc. The collector region 102, body region 108, body contact region 110, and doped region 113 are all formed by implanting ions of the second conductivity type into the drift region 100 through corresponding ion implantation processes. The field stop layer 101, buried layer 107, emitter region 109a, and sensing region 109b are all formed by implanting ions of the first conductivity type into the drift region 100 through corresponding ion implantation processes. The emitter region 109a and sensing region 109b are formed using the same ion implantation process.

[0054] Furthermore, the second conductivity type ion doping concentration in the body contact region 110 is greater than that in the body region 108. The first conductivity type ion doping concentration increases in the drift region 100, the buried layer 107, the field stop layer 101, and the emitter region 109a in that order. The ion concentrations in the body region 108, the collector region 102, and the doping region 113 may be the same or different.

[0055] It should be noted that in the cell structure of this embodiment, parameters such as the position, thickness, length, and concentration of the field stop layer 101, collector region 102, buried layer 107, body region 108, emitter region 109a, sensing region 109b, and doped region 113 can be modified according to design requirements. Parameters such as the position, depth, and width of the gate trench 104a and barrier trench 104b can also be modified according to design requirements. The electrical contact between the IGBT emitter and the emitter region 109a and body contact region 110 is ohmic, as is the electrical contact between the sampling sensing electrode Sense and the sensing region 109b, and between the sampling emitter and the doped region 113. This reduces device contact resistance and improves device performance.

[0056] In this embodiment, the IGBT emitter, sampling sensing electrode Sense, and sampling emitter are formed from the same metal film layer, using the same metal deposition and etching process. The material may include tungsten, copper, gold, or aluminum. The IGBT collector and sampling collector are formed from the same metal film layer, using the same metal deposition and etching process. The material may include tungsten, copper, gold, aluminum, or any other suitable metal or alloy.

[0057] In this embodiment, please combine Figure 2 and Figure 5 The IGBT emitter of the IGBT main cell I and the sampling emitter of the sampling cell II are connected as one to form the emitter E of the cellular structure of the IGBT device, the IGBT collector of the IGBT main cell I and the sampling collector of the sampling cell II are connected as one to form the collector C of the cellular structure of the IGBT device, and the gate of the IGBT main cell I serves as the gate G of the cellular structure of the IGBT device.

[0058] In this embodiment, when the first conductivity type is N-type and the second conductivity type is P-type, the device provided by the present invention is an N-channel IGBT device; when the first conductivity type is P-type and the second conductivity type is N-type, the device provided by the present invention is a P-channel IGBT device.

[0059] Please refer to Figure 4 , Figure 4 The output characteristic curve of sampling cell II under different VSE voltages is shown in Figure 2. Figure 5As shown, by connecting a sampling resistor Rsense in series between the sampling sensing electrode Sense and the sampling emitter, the current signal Isense can be converted into a voltage signal Vsense. The negative feedback provided by the sampling resistor Rsense prevents a sharp increase in the current Isense at the sampling sensing electrode Sense. Thus, adjusting the voltage difference VSE between the sampling sensing electrode Sense and the sampling emitter of sampling cell II not only adjusts the height of the electron channel barrier formed between the blocking trenches 104b, but also adjusts the ratio (Vsense / VCE) of the voltage signal Vsense output from the sampling sensing electrode Sense to the voltage difference VCE between the collector C and the emitter E. The sampling cell II in the present invention is effectively equivalent to connecting an electrostatic induction transistor to the periphery of the IGBT transistor formed by the IGBT main cell I.

[0060] Since the sampling resistor Rsense is required in this embodiment to convert the current signal Isense into the voltage signal Vsense, the sampling resistor Rsense may optionally be integrated into the cell structure of the IGBT device of the present invention. The sampling resistor Rsense may be, for example, a polysilicon resistor formed on the surface of the isolation dielectric layer 111. The two ends of the sampling resistor Rsense are ultimately electrically connected to the sampling sensing electrode Sense and the sampling emitter through corresponding metal interconnect processes.

[0061] In other embodiments of the present invention, the sampling resistor Rsense may be omitted in the cellular structure of the IGBT device. When the IGBT device formed by the cellular structure of the IGBT device is used in a specific scenario, the sampling resistor Rsense is connected between the sampling sensing electrode Sense and the sampling emitter through an access method such as a chip resistor.

[0062] It should be noted that the sampling cell II in the cellular structure of the IGBT device provided in this embodiment is integrated on the same drift region 100 as the IGBT main cell I, and therefore has compatible fabrication processes. In other words, the front-side fabrication process of the cellular structure of the IGBT device provided in this embodiment primarily involves fabricating the sampling cell and the main cell region on the front side of the silicon wafer. After completing the front-side fabrication process, the silicon wafer is flipped over and back-side fabrication is performed.

[0063] As an example, the front-side process of the cell structure of an IGBT device may include the following processes:

[0064] Step 1: Provide a semiconductor substrate of the first conductivity type as the drift region 100. After forming an oxide protection layer (not shown) on the surface of the drift region 100, etch the drift region 100 through photolithography and etching processes to produce the gate trench 104a required for the IGBT main cell I and the blocking trench 104b required for the sampling cell II in the drift region 100. The specific process parameters for etching the drift region 100 to form the gate trench 104a and the blocking trench 104b are well known to people in this technical field and will not be repeated here.

[0065] Step 2: An oxide layer is grown on the surface of the gate trench 104a and the blocking trench 104b to obtain a gate dielectric layer 105 covering the inner surface of the gate trench 104a and the blocking trench 104b. Further, through processes such as polysilicon deposition and back etching, a gate 106 is formed to fill the gate trench 104a and the blocking trench 104b. The specific process parameters for preparing the gate dielectric layer 105 and the gate 106 are well known to people in this technical field and will not be repeated here.

[0066] Step 3: Use ion implantation processes under different masks to form the buried layer 107, body region 108, body contact region 110, emitter region 109a required for the IGBT main cell I, and the doped region 113 and sensing region 109b required for the sampling cell II. In this process, a mask can be used to block the sampling cell area, and three different ion implantation processes can be used to sequentially form the buried layer 107, body region 108, and body contact region 110 required for the IGBT main cell I. Then, another mask can be used to block the IGBT main cell I area, and an ion implantation process can be used to form the doped region 113 required for the sampling cell II. Then, another mask can be used to block the corresponding area, and another ion implantation process can be used to simultaneously form the emitter region 109a required for the IGBT main cell I and the sensing region 109b required for the sampling cell II. Alternatively, a mask can be used to block the area of ​​the IGBT main cell I, and an ion implantation process can be used to form the doped region 113 required for the sampling cell II. Another mask can then be used to block the area of ​​the sampling cell, and three different ion implantation processes can be used to sequentially form the buried layer 107, body region 108, and body contact region 110 required for the IGBT main cell I. Another mask can then be used to block the corresponding areas, and another ion implantation process can be used to simultaneously form the emitter region 109a required for the IGBT main cell I and the sensing region 109b required for the sampling cell II. After all ion implantations are completed, a rapid annealing process can be performed to activate the ions in the buried layer 107, body region 108, body contact region 110, emitter region 109a, doped region 113, and sensing region 109b.

[0067] Step 4: Deposit an isolation dielectric layer 111 to cover and protect the buried layer 107, the body region 108, the body contact region 110, the emitter region 109a, the doped region 113 and the sensing region 109b, the gate trench 104a and the blocking trench 104b, etc., and perform the required contact hole etching on the isolation dielectric layer 111 to obtain a contact hole (not shown) penetrating the isolation dielectric layer 111.

[0068] Step 5: Deposit metal on the isolation dielectric layer 111 to obtain an emitter layer 112 filling each contact hole. Photolithography and etching are performed on the emitter layer 112 to form the IGBT emitter required for the IGBT main cell I and the sampling sensing electrode and sampling emitter required for the sampling cell II.

[0069] As an example, the back-side process of the cell structure of the IGBT device may include the following process: first, the back side of the silicon wafer is thinned to the required thickness through processes such as chemical mechanical polishing (CMP), then, the first conductive type ions are injected into the back side at high energy to form the required field stop layer 101, then, the second conductive type ions are injected into the back side to form the collector region layer 102, and then, metal is locally deposited on the back side to form the collector layer 103.

[0070] Based on the same inventive concept, an embodiment of the present invention further provides an IGBT device, which includes a plurality of cellular structures of the IGBT devices described above arranged in parallel.

[0071] Please refer to Figure 5 Each cell structure may include an IGBT main cell I, a sampling cell II, and a sampling resistor Rsense connected between a sampling emitter of the sampling cell II and a sampling sensing electrode Sense; or each cell structure does not have an integrated sampling resistor Rsense. In this case, the IGBT device further includes a sampling resistor Rsense provided in a one-to-one correspondence with each cell structure. The sampling resistor Rsense is connected between a sampling emitter of the sampling cell II and a sampling sensing electrode Sense of the corresponding cell structure by welding or wire connection.

[0072] Based on the same invention concept, please refer to Figure 5 An embodiment of the present invention further provides an IGBT short-circuit protection circuit, which includes the IGBT device, a protection circuit and a drive circuit described in the present invention. One end of the protection circuit is connected to the sampling sensing electrode Sense of the corresponding sampling cell of the IGBT device, and the other end is connected to one end of the drive circuit. The other end of the drive circuit is connected to the gate G of the corresponding IGBT main cell of the IGBT device.

[0073] Optionally, when a sampling resistor is not integrated in the cell structure of the IGBT device, the IGBT short-circuit protection circuit further includes a sampling resistor Rsense arranged in a one-to-one correspondence with the cell structure of the IGBT device, and the sampling resistor Rsense is connected between the sampling emitter E and the sampling sensing electrode Sense of the sampling cell in the corresponding cell structure of the IGBT device.

[0074] It should be noted that the protection circuit and the drive circuit can be any suitable circuits. The protection circuit and the drive circuit can be set in one-to-one correspondence with the cellular structure of the IGBT device respectively, and multiple cellular structures of the IGBT device can share the same protection circuit and the same drive circuit respectively.

[0075] The specific method for implementing short-circuit protection for IGBT devices using the IGBT short-circuit protection circuit of this embodiment is as follows: the Vsense signal (weak current signal) of the IGBT device is input into the protection circuit to implement voltage sampling of the IGBT device. The protection circuit further combines the IGBT drive signal and the Vsense signal of the drive circuit to determine whether the IGBT device is in a desaturated state, thereby implementing short-circuit protection for the IGBT based on the judgment result. In this process, the voltage difference VES between the Sense terminal and the emitter E can be further adjusted to achieve adjustable Vsense, and thus adjustable Vsense / VCE ratio. This can meet the voltage sampling requirements under different application conditions and achieve the purpose of safely and quickly detecting whether the IGBT is in a desaturated state.

[0076] In summary, the cellular structure of the IGBT device, the IGBT device and the IGBT short-circuit protection circuit of the present invention integrate a sampling cell in the cellular structure of the IGBT device to form an electrostatic induction transistor on the periphery of the IGBT transistor formed by the IGBT main cell. As a result, a weak current with an adjustable sampling voltage can be directly obtained on the sampling induction electrode of the sampling cell, thereby realizing real-time feedback of the voltage state of the collector of the IGBT transistor. According to the feedback result, it is possible to safely and quickly detect whether the IGBT device is in a protection cancellation state. The circuit has the advantages of simple structure, high integration, fast response, simplified peripheral circuit and low cost, compatibility with the original IGBT device manufacturing process, high system reliability, flexible and controllable use, and a wide range of applications.

[0077] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure are within the scope of the technical solution of the present invention.

Claims

1. A cell structure of an IGBT device, comprising an IGBT main cell and a sampling cell formed on a drift region of the same first conductivity type, characterized in that: The sampling cell includes: a first conductive type inductive region formed in a top surface layer of the drift region; Two doping regions of the second conductivity type are formed in the top of the drift region and are symmetrically distributed on both sides of the sensing region; Two blocking trenches are provided in one-to-one correspondence with the two doping regions, and each blocking trench is sandwiched between the corresponding doping region and the sensing region, wherein the depth of the blocking trench is less than the junction depth of the PN junction formed by the sensing region and the doping region; a sampling collector region of a second conductivity type, the sampling collector region being arranged at the bottom of the drift region; a sampling sensing electrode, disposed on the top surface of the drift region and electrically contacting the sensing region; a sampling emitter, disposed on the top surface of the drift region and arranged in one-to-one correspondence with and in electrical contact with the two doping regions; a sampling collector electrode, disposed on the bottom surface of the drift region and electrically contacting the sampling collector region; The IGBT main cell includes: a body region of a second conductivity type formed on top of the drift region; a body contact region of a second conductivity type formed in a top surface layer of the body region; An emitter region of a first conductivity type is formed in a top surface layer of the body region and is located on both sides of the body contact region; a buried region of a first conductivity type formed in the drift region and located below the body region; Two gate trenches are formed in the drift region and distributed on both sides of the body region, the depth of each gate trench is greater than the depth of the buried region, and each gate trench has a gate dielectric layer formed therein and is filled with a gate; An IGBT collector region of a second conductivity type, wherein the IGBT collector region is arranged at the bottom of the drift region; An IGBT emitter is disposed on the top surface of the drift region and is in electrical contact with both the emitter region and the body contact region; An IGBT collector is arranged on the bottom surface of the drift region and is in electrical contact with the IGBT collector region.

2. The cell structure of the IGBT device according to claim 1, wherein: The inner surface of the blocking trench is covered with an insulating dielectric layer and filled with a polysilicon layer; or, the blocking trench is completely filled with an insulating dielectric layer.

3. The cell structure of the IGBT device according to claim 1, wherein: The sampling cell further includes a sampling field termination region of a first conductivity type, wherein the sampling field termination region is formed at the bottom of the drift region and stacked on the collector region.

4. The cell structure of the IGBT device according to any one of claims 1 to 3, characterized in that: An electron channel is formed between the two blocking grooves, and the potential barrier height of the electron channel depends on the voltage difference between the sampling emitter and the sampling sensing electrode.

5. The cell structure of the IGBT device according to claim 3, wherein: The IGBT main cell further includes an IGBT field stop region of a first conductivity type, wherein the IGBT field stop region is formed at the bottom of the drift region and stacked on the IGBT collector region.

6. The cell structure of the IGBT device according to claim 5, characterized in that: The IGBT collector region and the sampling collector region are the same ion implantation layer at the bottom of the drift region; the IGBT emitter, the sampling sensing electrode and the sampling emitter are the same metal film, and the IGBT emitter and the sampling emitter are connected as a whole to form the emitter of the cell structure; the IGBT field stop region and the sampling field stop region are the same ion implantation layer at the bottom of the drift region; The IGBT collector and the sampling collector are formed from the same layer of metal film and are integrally connected to form the collector of the cell structure; the gate trench and the blocking trench are formed using the same trench etching process.

7. An IGBT device, characterized in that: A cell structure comprising a plurality of IGBT devices according to any one of claims 1 to 6 arranged in parallel.

8. The IGBT device according to claim 7, wherein: It also includes sampling resistors arranged in a one-to-one correspondence with the cellular structures, and the sampling resistors are connected between the sampling emitter and the sampling sensing electrode of the sampling cell in the corresponding cellular structure.

9. An IGBT short-circuit protection circuit, characterized in that: The device comprises a protection circuit, a drive circuit, and the IGBT device according to claim 7 or 8, wherein one end of the protection circuit is connected to the sampling sensing electrode of the sampling cell corresponding to the IGBT device, and the other end is connected to one end of the drive circuit, and the other end of the drive circuit is connected to the gate of the IGBT main cell corresponding to the IGBT device.

10. The IGBT short-circuit protection circuit according to claim 9, wherein: It also includes sampling resistors arranged in a one-to-one correspondence with the cell structures of the IGBT device, and the sampling resistors are connected between the sampling emitter and the sampling sensing electrode of the sampling cell in the corresponding cell structure of the IGBT device.

11. The IGBT short-circuit protection circuit according to claim 9, wherein: The protection circuit and the drive circuit are respectively arranged in one-to-one correspondence with the cellular structures of the IGBT device, or a plurality of cellular structures of the IGBT device respectively share the same protection circuit and the same drive circuit.

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